The invention involves the specific technical field of frames for spectacles, for which there is provision for the lateral arms to be of the interchangeable type.
Such a prerogative meets the ever-increasing requirement for providing methods for personalizing the frame which allow people to associate with the front portion of the same frame arms of different shapes, materials and colours, using arms of the interchangeable type. One of the problems which can be seen in this field of personalization of the spectacles involves the fact that the technology of the interchangeable coupling systems of the arms at the front portions of spectacles may involve limitations because they do not have adequate dexterity and competence, in addition to suitable tools, typically having to operate on components of small dimensions with fitting and coupling devices, some also with screw type systems of small dimensions, which are rather complex, fragile and which involve the risk of deformations and breakages, with the result that they are also disadvantageous in terms of efficacy and reliability. In the prior art, there are known solutions which allow the use in spectacles of quick engagement systems for interchangeable arms, in which a series of arms can be connected to an end of a hinge element which is intended for articulation to the front portion, by means of a quick-fit mechanism with a snap-fit connection, which can also be readily handled by an inexpert person who is not provided with particular tools.
An example of such a coupling system is known from U.S. Pat. No. 6,834,952. The system described therein provides for the retention means, which is capable of axially fixing the portions which are fitted to each other, to be formed as a resiliently flexible push-button which, when it is pressed until the retention means is disengaged, allows the quick disengagement of the arm from the frame so as to facilitate the interchangeability thereof. In the specific field of those quick-fit engagement systems, one of the limitations is the one connected with the stability of the connection. In fact, those systems though, on the one hand, making it easy and quick to change the arm, on the other hand do not ensure adequate efficacy in terms of stability in respect of the connection between the fitted portions, as a result of connection play during the sliding engagement of the connected portions, which necessarily have to be provided in order to allow ease of movement during engagement and disengagement of the arm with respect to the front frame portion associated therewith.